Once introduced into IV drug using populations, HIV has spread rapidly. The results represent an increase in the number of HIV-infected individuals in the commun presents potential for wide heterosexual and vertical transmission of the virus. We have documented a reasonable level of general knowledge of AIDS among IVDU in Sacramento area but have observed little impact of this knowledge on paraphernalia sharing, disinfection of paraphernalia, or high-risk sexual activity in this group. Thus, the stage is set for rapid spread of HIV within this population and to their heterosexual contacts. Indeed, we have documented a rise in HIV antibody prevalence from less than 1% in 12/85 to 3% in 3/87 in IVDU in Sacramento. We propose to implement and test the effectiveness of a comprehensive program of education and behavior modification among Sacramento IVDU, using our team consisting of a clinician-epidemiologist, a health educator, and epidemiologist and a trained drug counselor. Resources of the University of California, Davis Medical Center, Clinic forl AIDS and Related Disorders, the major drug abuse treatment programs in Sacramento, the Sacramento County Department of Health AIDS Project, and the University of California9 Davis Retrovirus Diagnostic Laboratory are also available to us. Data will be collected on 2,600 IVDU in Sacramento annually, including a cohort of 1,300 IVDU who will be intervidwed, educated, and tested for the presence of HIV antibody every four months. Seventy-five percent of these individuals will receive intensive re-education for avoidance of high-risk drug and sex activity, 25% individuals will be followed by an L.V.N., who will test them and do the follow-up questionnaire, but no intensive re-education will be provided. The knowledge, stated bebavior and HIV antibody status will be analyzed to evaluate the effectiveness of health educator (physician versus counselor versus counselor/former IVDU). Once developed, this education model could be applied to various cities in the U.S. with similar demographics. Success of this program shall be measured not only by evidence of slower spread of HIV but also by the large number of Government dollars and lives saved.